Discrete fracture models for fluid flow in fracture porous media

Speaker: Ziyao Xu (UND) Dates: 2024/04/05 Location: zoom, link Abstract:  As a result of geological processes and human activities, fractures are widely distributed in subsurface rocks. Depending on the degree of precipitation, fractures can act either as highly permeable, flow-preferential…

On the Activation Function Dependence of the Spectral Bias of Neural Networks

Speaker: Qinguo Hong (Missouri S&T) Dates: 2024/03/22 Location: MW 154 Abstract: Neural networks are universal function approximators which are known to generalize well despite being dramatically overparameterized. We study this phenomenon from the point of view of the spectral bias…

A High Order Geometry Conforming Immersed Finite Element for Elliptic Interface Problems

Speaker: Haroun Meghaichi (VT) Dates: 2024/02/08 Location: zoom Abstract:We present a high order immersed finite element (IFE) method for solving the elliptic interface problem with interface-independent meshes. The IFE functions developed here satisfy the interface conditions exactly and they have…

A Model-Based Approach for Continuous-Time Policy Evaluation with Unknown Lévy Process Dynamics

Speaker: Qihao Ye (UCSD) Dates: 2024/01/26 Location: zoom Abstract: This research presents a framework for evaluating policies in a continuous-time setting, where the dynamics are unknown and represented by Lévy processes. Initially, we estimate the model using available trajectory data,…

BDDC Algorithms for Advection-diffusion problems with HDG Discretizations

Speaker: Jinjin Zhang (OSU) Dates: 2023/11/09 Location: MA 105 Abstract: In this talk, I will talk about the balancing domain decomposition by constraints  (BDDC)  methods for the non-symmetric positive definite system arising from the hybridizable discontinuous Galerkin (HDG) discretization of advection-diffusion…

Realizability-Preserving DG-IMEX Method for a Two-Moment Model of Special Relativistic Transport

Speaker: Joseph Hunter (OSU) Dates: 2023/11/01 Location: MA 105 Abstract: Special relativistic transport models are important for describing the transport of neutrinos, with applications to supernovae and gravitational waves.  We study a two-moment model that evolves the Eulerian moments of…

Recent advances in discontinuous Galerkin discretization of Cahn–Hilliard–Navier–Stokes models for systems of two-phase flows

Speaker: Chen Liu (Purdue) Dates: 2023/10/26 Location: Zoom, link Abstract: Efficient and accurate pore-scale fluid dynamics simulators have important applications in digital rock physics. One of the popular approaches for modeling two-phase fluid flow in micro-to-millimeter pore structures is to…

Introduction to Nonlocal Calculus

Speaker: Zhaolong Han (UCSD) Dates: 2023/10/20 Location: Zoom, link Abstract: There has been a growing interest in the study of nonlocal models as more general and sometimes more realistic alternatives to the conventional PDE models. In this talk, we will…

Optimal Error Estimates of Ultra-weak Discontinuous Galerkin Methods with Generalized Numerical Fluxes

Speaker: Yuan Chen (OSU) Dates: 2023/10/06 Location: MW154 Abstract: We study ultra-weak discontinuous Galerkin methods with generalized numerical fluxes for multi-dimensional high order partial differential equations on both unstructured simplex and Cartesian meshes. The equations we consider as examples are…

Combining Stochastic Parameterized Reduced-Order Models with Machine Learning for Data Assimilation and Uncertainty Quantification with Partial Observations

Speaker: Changhong Mou (UWM) Dates: 2023/09/29 Time: 4:10-5:10 (EST) Location: Zoom, link Abstract: A hybrid data assimilation algorithm is developed for complex dynamical systems with partial observations. The method starts with applying a spectral decomposition to the entire spatiotemporal fields,…